Darwin's last book wasn't about evolution — it was about earthworms

After 40 years of observation, Charles Darwin's final book, published in 1881, argued that earthworms churn and enrich soil on a massive geological scale, gradually burying ancient ruins and reshaping landscapes one small casting at a time. It reportedly outsold 'On the Origin of Species' in its first year.

— Charles Darwin, The Formation of Vegetable Mould, through the Action of Worms — 1881